The invention set forth in this specification pertains to new and improved dental facebows.
It is well established that dental facebows are utilized in measuring or determining the positions of the temporomandibular joints of a patient relative to the patient's maxillary teeth so that such relative positions may be transferred to a dental articulator. Such measurements are useful in the operation of the articulator for a variety of dental purposes. It is not considered that an understanding of the present invention requires any detailed explanation as to the reasons why such relative measurements are made and the reasons why such measurements are transferred to the articulator. These items are considered to be well established in the dental field.
It is, however, considered necessary to understand that prior dental facebows have been constructed so as to include side arms connected by a mechanical connecting structure. As used these side arms are located at the sides of the head of a patient while the connecting structure is located generally in front of the face of the patient. These prior facebows have normally been constructed so as to include a frame or frame-type structure including a so-called dental fork or an equivalent member mounted on the connecting structure so that the dental fork can be inserted within the patient's mouth against or adjacent to the maxillary teeth in making an impression of the patient's maxillary teeth. During the use of the facebow the dental fork holds such an impression.
Such prior facebows have been constructed in a number of different ways. Many such prior units have been constructed so that so-called styli or positioning members located on ends of the arms are separately moved relative to the head of a patient after the arms are secured so as to be immobile with respect to one another and after the dental fork is located in an appropriate position in the mouth. Structures of this type are considered to be relatively difficult to use in obtaining accurate measurements.
It is considered this has led to the development of another type of facebow structure in which two generally C-shaped arms are pivotally connected by a link so that these arms have ends which are adapted to be located on opposite sides of the head of a patient and so that these arms have overlapping ends which may be clamped together. This type of dental facebow normally carries a framework including a dental fork on the connecting link. Structures of this type are considered to be disadvantageous in making accurate measurements which can be transferred to an articulator because of the linkage system employed. The type of linkage used in such dental facebows shifts the position of a dental fork relative to the ends of the arms used for measurement purposes slightly as a result of the pivoting of the arms with respect to the connecting link.